The subject invention relates to a data gathering panel for use in communication systems wherein the data gathering panel is located remotely from other remote stations one of which may include a central processing unit and, more particularly, to a data gathering panel which can accommodate a wide variety of analog and digital sensors, which provides an analog-to-digital converter capable of converting analog values from a wide variety of analog sensors to standard digital values, and which provides a programmable read-only memory for storing information which is useful by the processor in processing information wherein the programmable read-only memory can be configured and/or reconfigured from a station remote from the data gathering panel.
In an effort to reduce the complexity and attendant unreliability and installation costs of systems for controlling a building's air conditioning plant, energy consuming equipment, and the like, communication systems were developed wherein a central station communicated with a plurality of remote stations over a communication channel so that various points around a building could be sensed and various control units could be controlled. A typical remote station consisted of an interface circuit having a remote state address so that all remote stations were connected over a single pair of wires to the central station. Communication over this pair of wires was established between the central station and the remote stations so that the central station read the status points of the remote stations and commanded the control apparatus associated with the remote station. Therefore, the interface apparatus at the remote station simply served as a vehicle for collecting data to be reported to a central station and for responding to control messages sent by the central station to operate the various control apparatus associated with the remote station.
The evolution of such building automation and fire and security systems in recent times is beginning to influence system architecture. For example, there is a tendency for increasing the size of such building control systems to accommodate the ever increasing size of office buildings which are being constructed and to handle the increased number of sensing, control, fire and security points in new and existings buildings. The increased size and complexity of the system architecture and the increasing variety of tasks to be performed by the hardware has placed an enormous burden on the central processing units of such systems. Moreover, it may be necessary or desirable in some systems to eliminate the central processing unit altogether and to spread the control functions normally performed by a central station among a plurality of stations located throughout the communication system. These factors, among others, require that the system be capable of processing information at locations other than a central station. Thus, the remote stations (or data gathering panels) located throughout the communication system are beginning to be provided with computerized data processing capability made feasible by the microprocessor.
Since it is the data gathering panel which must now perform a portion of the data processing involved in the system as a whole, these data gathering panels must interface with the sensing and control points in such building automation and fire and security systems. The data gathering panel must acquire data from sensors connected thereto and must process the data acquired from these sensors to effect certain control decisions with respect to the control apparatus also connected to the data gathering panel. It would be beneficial if such data gathering panels were universal in nature such that they could be connected to any type of analog sensor or digital sensor without providing special connecting interface hardware between the sensor and the data gathering panel. If the data gathering panel is to be connected to sensors having widely varying characteristics, and if the data gathering panel is to process the data received from the sensors to effect control of the loads connected thereto, the data gathering panel must be able to convert the analog input signals from analog sensors having different characteristics into digital values for processing by the processing apparatus. If the use of separate hardware for each type of sensor is to be avoided, it is necessary to provide memory associated with the processing apparatus located in the data gathering panel for storing the programs and data files associated with the sensors and control apparatus, and it is desirable, therefore, to be able to change this memory from a remote location.